An eye can have various disorders which affect the crystalline lens of the eye. One of the most common disorders is cataracts, which is a clouding of the crystalline lens. The conventional treatment for cataracts is removal of the crystalline lens and replacement of the lens with an artificial or intraocular lens (IOL).
Once an IOL is implanted, however, it generally has a fixed refractive power. This presents a problem with respect to both far and near vision. With respect to far vision, the diopter power of the IOL is generally not capable of perfect vision—i.e. 20/20. This problem is due to the fact that the refractive power of the IOL must be chosen prior to implantation and thus can only be approximated. Since the diopter power can only be approximated, most patients will require at least a ±1.00 diopter power correction along the optical path to provide perfect vision. With respect to near vision, an artificial lens results in a loss of accommodation (i.e., the process of focusing the eye between far objects and near objects).
In an attempt to avoid loss of accommodation, a technique has been developed that involves removing the crystalline lens and leaving the capsular bag that holds the crystalline lens substantially intact. Once the lens has been removed, a new lens is created in situ by filling the capsular bag with a liquid material and polymerizing or curing the liquid to form an IOL in situ. The newly formed lens has characteristics that approximate the function of a crystalline lens. By leaving the capsular bag substantially intact, the newly formed IOL will be able to focus the eye between near and far objects better than if the capsular bag is removed since the capsular bag is attached to the interior of the eye by the zonular ligaments.
This in situ replacement of a crystalline lens has been referred to as a phaco-ersatz procedure. U.S. Pat. No. 6,598,606 B2 to Terwee et al. discloses a method of forming an IOL in situ using a photo-curable polymerizable material, and is herein incorporated by reference in its entirety.
One drawback to the phaco-ersatz procedure described in the Terwee patent is that the shape of the lens, after creation, is not particularly controllable. That is, the shape of the lens is largely dictated by the shape of the capsular bag, and a surgeon has little control over the shape of the lens. Consequently, the newly formed lens is unlikely to provide the exact refractive power necessary to provide perfect vision. Therefore, as with a conventional IOL at least a ±1.00 diopter power correction will be required to obtain perfect vision. Furthermore, the newly formed lens will not compensate for any optical aberrations located elsewhere in the eye, such as astigmatism in the cornea.